This invention relates to a generator stator end winding seal design and, more particularly, to a seal ring that effectively seals the gap between an air shield and an end winding inner surface in a generator stator.
A reverse flow generator design requires an air flow chamber wall at an end winding area, which is made up by a second row of the end winding blocking, a seal, and the outer surface of an air shield. With proper sealing, air flow will flow radially through the outboard section of the end winding first and then flow back at the inboard section of the end winding, thereby cooling the stator end winding. FIG. 1 illustrates a desired air flow path in a reverse flow generator.
The end winding in a generator stator has an irregular inner surface due to its construction, and air leakage, both radially and axially is a concern. That is, sufficient air flow across the end winding is necessary to prevent overheating. The stator end winding is configured with the air shield to direct the flow along a predetermined air flow path to cool the end winding. Air leakage along the flow path is thus contrary to design considerations, and thereby increases the end winding susceptibility to overheating.
In addition, in the stator end winding area, configuration components attached to the end winding area must be checked closely for insulation material wear out due to vibration, etc. Thus, a seal in the end winding area should be constructed of materials or particularly configured to reduce insulation material wear due to relative motion. At a minimum, a component in the end winding area such as a seal ring should be fixed securely on the end winding. In this context, however, because the top stator bars will have been previously installed, the work space in the end winding area is limited, which may cause manufacturing productivity issues and may increase assembly cycle time.